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Here, we present a protocol for electrotaxis of large epithelial cell sheets without compromising the integrity of cell epithelia in a high-throughput customized directed current electrotaxis chamber. We describe the fabrication and use of polydimethylsiloxane stencils to control the size and shape of human keratinocyte cell sheets. We detail cell tracking, cell sheet contour assay, and particle image velocimetry to reveal the spatial and temporal motility dynamics of cell sheets. This approach is applicable to other collective cell migration studies. For complete details on the use and execution of this protocol, please refer to Zhang et al. (2022).1.

Directional migration initiated at the wound edge leads epithelia to migrate in wound healing. How such coherent migration is achieved is not well understood. Here, we used electric fields to induce robust migration of sheets of human keratinocytes and developed an in silico model to characterize initiation and propagation of epithelial collective migration. Electric fields initiate an increase in migration directionality and speed at the leading edge. The increases propagate across the epithelial sheets, resulting in directional migration of cell sheets as coherent units. Both the experimental and in silico models demonstrated vector-like integration of the electric and default directional cues at free edge in space and time. The resultant collective migration is consistent in experiments and modeling, both qualitatively and quantitatively. The keratinocyte model thus faithfully reflects key features of epithelial migration as a coherent tissue in vivo, e.g. that leading cells lead, and that epithelium maintains cell-cell junction.

BackgroundDiagnostic laparoscopy (DL) is a key component of staging for locally advanced gastric adenocarcinoma (GA). We hypothesized that utilization of DL varied between safety net (SNH) and affiliated tertiary referral centers (TRCs).MethodsPatients diagnosed with primary GA eligible for DL were identified from the US Safety Net Collaborative database (2012-2014). Clinicopathologic factors were analyzed for association with use of DL and findings on DL. Overall survival (OS) was analyzed by Kaplan-Meier method.ResultsAmong 233 eligible patients, 69 (30%) received DL, of which 24 (35%) were positive for metastatic disease. Forty percent of eligible SNH patients underwent DL compared to 21.5% at TRCs. Lack of insurance was significantly associated with decreased use of DL (OR 0.48, p

BackgroundHispanic patients have a higher incidence of gastric cancer when compared to non-Hispanics. Outlining clinicodemographic characteristics and assessing the impact of ethnicity on stage-specific survival may identify opportunities to improve gastric cancer care for this population.MethodsPatients with gastric cancer in the US Safety Net Collaborative (2012-2014) were retrospectively reviewed. Demographics, clinicopathologic characteristics, operative details, and outcomes were compared between Hispanic and non-Hispanic patients. Early onset gastric cancer was defined as age

Background and objectivesPerioperative therapy is a favored treatment strategy for gastric cancer. We sought to assess utilization of this approach at safety net hospitals (SNH) and tertiary referral centers (TRC).Materials and methodsPatients in the US Safety Net Collaborative (2012-2014) with resectable gastric cancer across five SNH and their sister TRC were included. Primary outcomes were receipt of neoadjuvant chemotherapy (NAC) and perioperative therapy.ResultsOf 284 patients, 36% and 64% received care at SNH and TRC. The distribution of Stage II/III resectable disease was similar across facilities. Receipt of NAC at SNH and TRC was similar (56% vs. 46%, p = 0.27). Compared with overall clinical stage, 38% and 36% were pathologically downstaged at SNH and TRC, respectively. Among patients who received NAC, those who also received adjuvant chemotherapy at SNH and TRC were similar (66% vs. 60%, p = 0.50). Asian race and higher clinical stage were associated with receipt of perioperative therapy (both p

BackgroundWhile parenchymal hepatic metastases were previously considered a contraindication to cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC), liver resection (LR) is increasingly performed with CRS/HIPEC.MethodsPatients from the US HIPEC Collaborative (2000-2017) with invasive appendiceal or colorectal adenocarcinoma undergoing primary, curative intent CRS/HIPEC with CC0-1 resection were included. LR was defined as a formal parenchymal resection. Primary endpoints were postoperative complications and overall survival (OS).ResultsA total of 658 patients were included. About 83 (15%) underwent LR of colorectal (58%) or invasive appendiceal (42%) metastases. LR patients had more complications (81% vs. 60%; p = .001), greater number of complications (2.3 vs. 1.5; p

BackgroundPostoperative complications (POCs) are associated with worse oncologic outcomes in various cancer histologies. The impact of POCs on the survival of patients with appendiceal or colorectal cancer after cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) is unknown.MethodsThe US HIPEC Collaborative (2000-2017) was reviewed for patients who underwent CCR0/1 CRS/HIPEC for appendiceal/colorectal cancer. The analysis was stratified by noninvasive appendiceal neoplasm versus invasive appendiceal/colorectal adenocarcinoma. The POCs were grouped into infectious, cardiopulmonary, thromboembolic, and intestinal dysmotility. The primary outcomes were overall survival (OS) and recurrence-free survival (RFS).ResultsOf the 1304 patients, 33% had noninvasive appendiceal neoplasm (n = 426), and 67% had invasive appendiceal/colorectal adenocarcinoma (n = 878). In the noninvasive appendiceal cohort, POCs were identified in 55% of the patients (n = 233). The 3-year OS and RFS did not differ between the patients who experienced a complication and those who did not (OS, 94% vs 94%, p = 0.26; RFS, 68% vs 60%, p = 0.15). In the invasive appendiceal/colorectal adenocarcinoma cohort, however, POCs (63%; n = 555) were associated with decreased 3-year OS (59% vs 74%; p

When a constraint is removed, confluent cells migrate directionally into the available space. How the migration directionality and speed increase are initiated at the leading edge and propagate into neighboring cells are not well understood. Using a quantitative visualization technique-Particle Image Velocimetry (PIV)-we revealed that migration directionality and speed had strikingly different dynamics. Migration directionality increases as a wave propagating from the leading edge into the cell sheet, while the increase in cell migration speed is maintained only at the leading edge. The overall directionality steadily increases with time as cells migrate into the cell-free space, but migration speed remains largely the same. A particle-based compass (PBC) model suggests cellular interplay (which depends on cell-cell distance) and migration speed are sufficient to capture the dynamics of migration directionality revealed experimentally. Extracellular Ca2+ regulated both migration speed and directionality, but in a significantly different way, suggested by the correlation between directionality and speed only in some dynamic ranges. Our experimental and modeling results reveal distinct directionality and speed dynamics in collective migration, and these factors can be regulated by extracellular Ca2+ through cellular interplay. Quantitative visualization using PIV and our PBC model thus provide a powerful approach to dissect the mechanisms of collective cell migration.